# MP4 export fails when output path contains non-ASCII characters (e.g. Japanese)

**URL:** https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357
**Category:** Development
**Created:** [December 9, 2025, 7:06am UTC](https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357 "2025-12-09T07:06:55Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![Japan\_OpenDEM](https://discourse.paraview.org/user_avatar/discourse.paraview.org/japan_opendem/32/17298_2.png) [@Japan\_OpenDEM](https://discourse.paraview.org/u/Japan_OpenDEM)
#### Post date: [December 9, 2025, 7:06am UTC](https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357/1 "2025-12-09T07:06:55Z")

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When exporting an MP4 video, ParaView cannot correctly generate the file if the output path contains non-ASCII characters (e.g., Japanese).

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### Author: ![ben.boeckel](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [December 9, 2025, 3:20pm UTC](https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357/2 "2025-12-09T15:20:05Z")

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I imagine we need to use `vtksys::fstream` instead somewhere.Is this on Windows?

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### Author: ![ben.boeckel](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [December 10, 2025, 2:58am UTC](https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357/3 "2025-12-10T02:58:32Z")

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Cc: @mwestphal @todoooo Might be of interest to you.

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<div class="post-metadata">

### Author: ![todoooo](https://discourse.paraview.org/user_avatar/discourse.paraview.org/todoooo/32/2819_2.png) [@todoooo](https://discourse.paraview.org/u/todoooo)
#### Post date: [December 10, 2025, 8:14am UTC](https://discourse.paraview.org/t/mp4-export-fails-when-output-path-contains-non-ascii-characters-e-g-japanese/17357/4 "2025-12-10T08:14:18Z")

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It’s hard to comment without having the steps to recreate but FFMPEG `avio_open` expects a UTF-8 filename, so I would say the text provided has not been properly converted from UTF-16 on Windows.

```auto
  if (avio_open(&this->avFormatContext->pb, this->avFormatContext->filename, AVIO_FLAG_WRITE) < 0)
  {
    vtkGenericWarningMacro(<< "Could not open " << this->Writer->GetFileName() << ".");
    return 0;
  }

```

If the skybox movie representation is being used then the filename comes from request data.

```auto
int vtkSkyboxMovieRepresentation::RequestData(
vtkInformation* request, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
if (inputVector[0]->GetNumberOfInformationObjects() == 1)
{
vtkTable* input = vtkTable::GetData(inputVector[0], 0);
if (input->GetNumberOfRows() > 0 && input->GetNumberOfColumns() > 0)
{
this->DummyPolyData->GetFieldData()->ShallowCopy(input->GetRowData());

  std::string text = vtkExtractString(this->DummyPolyData);
  this->FileName = text;
}

}
else
{
this->DummyPolyData->Initialize();
}
this->DummyPolyData->Modified();
return this->Superclass::RequestData(request, inputVector, outputVector);
}

```